A network element (such as a router or switch) transmits and receives network data using one or more ports of that network element. Each port on the network element has a physical link speed that limits the rate at which network data can be transmitted from that port. The network element uses one or more queues to store the network data that is to be transmitted from one of the ports of the network element. The maximum data that a queue stores is determined by the available buffer memory and a buffer configuration for the queue. When the amount of network data that is to be transmitted by one of the ports on a network element, or the overall data transmitted by a network element, is greater than the port or network element can handle within a given period, network congestion can occur, resulting in increased latency for network data propagation through the nodes on the network.
In many environments, but particularly in high performance computer networking and data center environments, it can be essential for network administrators to attain a complete understanding of network latency within and between network elements on the network. For example, performance and latency analysis is a key task in maintaining low latency, high-speed data networks such as financial trading networks. Several tools exist in the art to monitor network latency on such networks. Such tools include optical taps, synthetic traffic injection, data captures, or other methods that include the sampling or monitoring of selected regions of the network. One challenge presented by the use of such tools is that any time stamping or latency analysis is performed on only a subset of the network. A second timing network may be used to gain detailed analysis of network performance, but at a greatly increased cost of implementation.